The present invention relates to flexible covers or tarping systems for open-topped containers. The invention is particularly related to tarping systems for use with hauling vehicles, such as dump trucks, where the flexible cover or tarpaulin is extended across the open top of the truck body/container.
Many hauling vehicles, such as dump trucks, include open-topped containers useful for hauling or storing various materials. For example, in a typical dump truck application, the dump body is used to haul a variety of particular material, such as gravel, aggregate or similar products. In addition, some hauling vehicles carry organic materials, such as grain or produce.
Depending upon the nature of the materials stored in the open-topped container, it is often desirable to provide a cover for the container. Of course, rigid covers are well known that may be hinged from end of the container body. These rigid covers have gradually given way in the trucking industry to flexible tarping systems because the flexible tarpaulin can be easily stowed when a cover is not necessary, such as when the dump truck is being loaded. Moreover, the flexible tarp is much easier to deploy than a rigid cover, and is easier to replace when it becomes worn or damaged. Furthermore, in some instances the flexible tarp provides a tighter environmental seal for the contents of the container than is provided by a rigid cover.
A variety of tarping systems have been developed that are geared, to particular hauling vehicle applications. Once such tarping system for use with dump trucks is the Easy Pull(copyright) tarping system of Aero Industries, Inc. The Easy Pull(copyright) system includes a flexible tarp that is wound around a spool at one end of a dump bed. A rope attached to the free end of the tarp can be used to unwind the tarp from the roller to extend along the length of the dump bed.
Another cover system particularly suited for open-topped containers on hauling vehicles is the Easy Cover(copyright) tarping system, also of Aero Industries, Inc. The Easy Cover(copyright) tarping system includes a U-shaped bail member that is pivotally mounted at its end to the base of the container body. The horizontal section of the U-shaped bail is attached to the tarp, while the free ends of the vertical elements are pivotably mounted to the truck body. In one application, the Easy Cover(copyright) tarping system allows the tarp to be manually pulled in a sweeping arc over the container load.
In another application of the Easy Cover(copyright) system, an actuation mechanism is provided that automatically pivots the U-shaped bail member to deploy the tarp over the load within the open-topped container. When the actuation mechanism is released, it automatically pivots the bar, thereby unfurling the tarp from the tarp roller at the front of the vehicle. A hand crank or powered motor can be provided to rotate the tarp roller to retract or wind the tarp when it is desired to open the container top.
A problem with all of the above cover/tarp systems and other cover systems is that once the tarp or cover is deployed, the tarp is not necessarily taut or tight against the load carried by the container. Since the cover is not taut against the load during transportation, there is a tendency for wind, which may flow across or beneath the cover, to cause billowing and flapping of the cover. Because of the elevated mounting position of the cover housing, a persistent void is created by such prior art cover systems. Such a void allows wind to continue to flow beneath the cover causing further billowing and flapping, accelerating cover wear and causing excessive stress in the system. Wear and fatigue in the cover system degrades the effectiveness of the cover system.
In order to alleviate the above condition, various systems have been developed that are designed to keep the cover relatively taut when extended. One simple manner of keeping the cover taut is provided in U.S. Pat. No. 4,516,802 issued to Compton on May 14, 1985 (hereinafter xe2x80x9cthe ""802 Patentxe2x80x9d). The ""802 Patent uses a flexible cord strung around the periphery of the cover. The cord engages a plurality of hooks secured to the outside of the container in order to maintain the cover taut. This approach, however, is not desirable since it requires a user to manually connect the flexible cord to the hooks.
U.S. Pat. No. 4,341,416 issued to Richard on Jul. 27, 1982 (hereinafter xe2x80x9cthe ""416 Patentxe2x80x9d) discloses another manner of trying to maintain the cover taut over a load. In one embodiment of the ""416 Patent, a plurality of arms or links extend from the headboard to the cover. The links are adapted to allow the front edge of the cover to swing from open to closed positions and to accumulate or roll-up on a cover take-up roll.
Another example is found in U.S. Pat. No. 5,031,955 issued to Searfoss on Jul. 16, 1991 (hereinafter xe2x80x9cthe ""955 Patentxe2x80x9d). The ""955 Patent utilizes a tension assembly having a tension bail extending over the front of the cover from outside of the container. The tension bail includes legs extending along the outside of the container and attached to the cover (rear) bail legs. The tension bail is thus lowered when the cover is extended by the cover bail. A similar mechanism is disclosed in U.S. Pat. No. 5,957,523 issued to Haddad, Jr. on Sep. 28, 1999 (hereinafter xe2x80x9cthe ""523 Patentxe2x80x9d). The ""523 Patent discloses a tensioning device for use with a flexible cover on an open top container that is operative to maintain the cover taut. A tensioning bar is spring biased downwardly onto the top of the cover adjacent the truck cab by a pair of oppositely situated arms that extend from the outside of the upper cab area.
The ""955 Patent, the ""523 Patent and other similar mechanisms operate a tensioning bar from the outside of the container. Consequently, the tensioning bar cannot extend into the container (i.e. through a plane defined by the top surface of the container) in order to have the cover accommodate loads of various volumes. Additionally, the hold-down systems epitomized by the ""955 and ""523 Patents utilize spring biasing to push down upon the tensioning arm and thus the cover.
Another system, marketed by the assignee of the present invention, is the Stay-Put(copyright) hold-down system. The Stay-Put(copyright) system utilizes a hold-down system having a hold-down bar that is interior to the container. The hold-down bar of the Stay-Put(copyright) system is thus able to extend below the plane of the top of the container. The hold-down bar is coupled to rigid arms that are mounted inside of the walls of the container but above the tension arm. The Stay-Put(copyright) hold-down system, however, still exerts a bias or pressure downwardly from the top onto the cover.
There remains a need for an improved tension/hold-down system or system for holding a cover such as a flexible tarp down and/or taut when in its extended or deployed position. The hold-down must be capable of keeping the cover tightly down over a load in the container, even against road vibration and wind force generated when traveling at highway speeds. In addition, the improved system would be easily installed, and potentially capable of retrofit to existing flexible tarping systems. The improved hold-down system would also provide a more positive retention force against the cover.
In order to address these unresolved needs, the present invention provides a hold-down system for a cover or cover system for an open-top container that is primarily disposed interior of the container/container walls. The hold-down system includes a hold-down member that is disposed over the outer surface of the cover. The hold-down member is pulled downwardly onto the cover to take up slack in the cover by a biasing mechanism that is disposed within the interior of the container. In this manner, the cover is pulled downwardly (tensioned) over the load when the cover is extended. Preferably, the hold-down member is pulled below the top of the container so that the cover is consequently pulled at or below the top of the container for at least a portion of the length of the cover during cover extension and/or deployment. When the cover is retracted, the hold-down member maintains tension on the cover.
As the cover is extended or deployed, the present biasing mechanism maintains a downward pull against the outside of the cover. This takes up slack in the cover and/or keeps the cover taut and thus directs the cover toward and onto a load in the container. In the retracted mode, tension is maintained against the cover while allowing almost full cover retraction. In a preferred embodiment, the biasing mechanism is mounted toward the front of the container.
The biasing mechanism, in one form, may include biased reels, spools or the like, and associated cordage, mounted on opposite sides of the container. The cordage can be situated (e.g. wound) on respective biased reels and is operative to be attached at a free end to the hold-down member. In the preferred embodiment, the cordage is wire cable. The biased reels can be biased by a torsion spring that is calibrated to maintain a sufficient tension on the cordage, and ultimately a sufficient downward force applied by the hold-down member to the cover. Sufficient upward force (e.g. pulling) overcomes the bias of the reels to extend the length of the cordage and the position of the hold-down member relative to the truck container top, load, or cover.
The cordage is coupled to the hold-down member preferably at opposite ends thereof. The hold-down member can have ends configured to be connected to the cordage, or can include a spindle onto which the cordage is attached or connected. Alternatively, the cordage can pass through the hold-down member, with the opposite ends of the cordage engaging a biasing mechanism at opposite sides of the container.
The biasing mechanism is calibrated to exert a pulling or downward force against the cover without creating undue stress on the cover. This force can be overcome to allow the hold-down member to move relative to the biasing mechanism/system in response to tension in or movement of the tarp as it is deployed or retracted.
According to an embodiment of the subject invention, there is contemplated a hold-down system for a cover/cover system for an open-topped container, in which the cover/cover system includes a tension or biasing mechanism mounted interior of the container and a hold-down member operatively coupled to the tension mechanism and interacting with the cover.
In one form there is provided a hold-down system for maintaining a cover for an open-topped container taut. The hold-down system includes a hold-down member that is adapted to be disposed interior of the cover. A biasing mechanism is disposed interior of the open-topped container. Cordage couples the hold-down member to the biasing mechanism. The biasing mechanism exerts a constant downward tension against the hold-down member and thus the cover.
In another form of the invention, there is provided a hold-down system that includes a biasing subsystem, a hold-down member, and means for operatively coupling the biasing subsystem to the hold-down member. The biasing subsystem is situated within the container. The hold-down member is adapted to extend along an outside surface of the cover. The biasing subsystem generates a constant pull-down force on the hold-down member wherein the hold-down member provides a constant force against the cover.
In still another form of the invention, there is provided a method of maintaining a cover for an open topped container taut. The method includes: (a) providing a hold-down member that is adapted to extend a distance along an outside surface of the cover; (b) providing a first biasing mechanism on a first inside surface of the container, the first biasing mechanism operative to provide a constant tensioning against a first connecting member; (c) providing a second biasing mechanism on a second inside surface of the container, the second biasing mechanism operative to provide a constant tensioning against a second connecting member; and (d) coupling the first and second connecting members to the hold-down member such that the constant tensioning is translated to the hold-down member.
One object of the present invention is to provide a biasing mechanism for holding a deployed tarp down over a load within a container, even when the tarp is subject to road vibration and wind.
A further benefit of the invention is realized in features that allow the invention to be retrofitted to existing tarping systems. These and other benefits and objects of the invention will be appreciated upon consideration of the following written description and accompanying figures.